Fishes of the Western North Atlantic 22g 



Key to Species 



I a. Caudal about V4 of total length} origin of anal only a little posterior to origin of ist 

 dorsal; distance from tip of snout to angle of mouth only about V4 as long as from 

 snout to 5th gill opening; length of snout in front of mouth about V3 as great as width 

 of mouth. acrages Jordan and Snyder, 1904. 



Japan.' 



lb. Caudal only about y^ of total length; origin of anal considerably posterior to origin 

 of 1st dorsal; distance from snout to angle of mouth Y2 as great as from snout to 5th 

 gill opening or greater; length of snout in front of mouth about V2 as great as width of 

 mouth. microdon Brito Capello, 1 867, p. 229. 



Pseudotriakis microdon Brito Capello, 1867 



Figure 40 



Study Material. None. 



Distinctive Characters. Separable from all other Atlantic sharks by the great length of 

 its first dorsal fin. 



Description. Proportional dimensions in per cent of total length. Specimen, 2,950 

 mm., from Amagansett, N. Y. (after Goode and Bean). 



Trunk at origin of ist dorsal: breadth 8.5; height 12.0. 



Snout length in front of: mouth 3.0. 



Eye: horizontal diameter 2.3. 



Mouth: breadth 9.0. 



Nostrils: distance between inner ends 4.2. 



Gill ofening lengths: ist 2.6. 



First dorsal fin: greatest height 3.2; length of base 22.7. 



Second dorsal fin: greatest height 5.4; length of base 12.5. 



Anal fin: greatest height 4.0; length of base 8.5. 



Caudal fin: upper margin 18.O; lower anterior margin 7.7. 



Pectoral fin: greatest length 1 1.2; greatest width 8.0. 



Distance from snout to: ist dorsal 34.O; 2nd dorsal 67.O; upper caudal 82.O; pec- 

 toral 20.0; pelvics 5 6.0; anal 70.7. 



Intersface between: ist and 2nd dorsals 10.5; 2nd dorsal and caudal 3.9. 



Male embryo, ready for birth, 850 mm., from Iceland (after measurements by Saemunds- 

 son). 



Snout length in front of: mouth 5.3. 



First dorsal fin: height 4.1 ; length 21.2. 



3. For these and other differences in proportionate measurements, see Jordan and Snyder (Smithson. misc. Coll., ^5, 

 1904: 233). The original spelling was "acrales," but Garman (Mem. Harv. Mus. comp. Zool., 36, 1913: 105) 

 has pointed out that this was a misprint. 



